They claim they identify causality but I don't see how that's possible based on what's written here. The presence (or lack thereof) of frats is going to change

They claim they identify causality but I don't see how that's possible based on what's written here. The presence (or lack thereof) of frats is going to change the applicant pool to begin with. And once they are present, there are going to be differences between who applies to be in a frat and who doesn't.